Railway track circuit apparatus



1938 Q F. H. NICHOLSON 2,127,134

RAILWAY TRACK CIRCUIT APPARATUS Filed July 25, 1935 INVENTOR Fkanli [1.1%012015012. Q- JEILMQ' HIS ATTORNEY Patented Aug. 16, 1938 UNITED STATES 2,127,134 RAILWAY TRACK CIRCUIT APPARATUS Frank H. Nicholson, Wilkinsburg, Pa, .assignor to The Union Switch & Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application July 25, 1935, Serial No. 33,083

1 Claim.

My invention relates to railway track circuit apparatus and more specifically to apparatus of the coded type wherein the energy is supplied to the rails in the form of impulses.

5 In coded direct current track circuits it has been found that the track rails resting on the ties and ballast may constitute a form of storage battery which may store energy during the on periods of the impulses. This stored energy dis- 10 charges into the code following track relay during the off periods of the impulses with the result that the normal operation of the relay is interfered with and in some instances the release of the relay is prevented entirely. One

15 feature of my invention is the provision of means for minimizing the effect of this stored energy on the operation of the code following track relay.

I will describe two forms of apparatus embodying my invention, and will then point out 20 the novel features thereof in the claim.

The accompanying drawing is a diagrammatic view illustrating two forms of apparatus embodying my invention. That is, as hereinafter will be explained more in detail, the control of 5 the coded track circuit current for section IT embodies one form of my invention and the control of the coded track circuit current for section 2T embodies another form of my invention.

Referring now to the drawing, the reference 3 character X designates a stretch of railway track over which traffic normally moves in the direction indicated by the arrow. The rails I and 2 of track X are divided by insulated joints 3 into sections IT and ET. Each section IT and 2T is provided with a code following track relay connected across the rails at the entering end of the section and designated by the reference character TR with a distinguishing prefix, and with a source of direct current designated by the reference 40 character B with a distinguishing prefix, for supplying energy to the rails at the other end of the section.

The battery IB, in series with a resistor 4, is connected to the rails of section IT by means of a front point of contact 5 of a current coding relay designated by the reference character C.

The coding relay C is controlled in any convenient and well-known manner, not shown in the drawing, so that front point of contact 5 50 closes and opens a definite and predetermined number of times per minute in accordance with traflic conditions in advance. For example, if the track section immediately in advance of section IT is occupied by a train, the relay C may 55 operate 80 times per minute, whereas, if this advance section is unoccupied, the relay may operate 180 times per minute.

The code following track relay ITR operates its contact 6 in accordance with the impulses supplied to the rails'by relay C and may be em- 5 ployed for controlling a traffic governing device, such as a signal, in accordance with the character of the code received; or, as here shown, may be utilized for controlling the supply of coded current to the track section next in rear. 10

In the latter event, the relay ITR simply repeats the code supplied by coding relay C, and the sections IT and ET are considered to be one block. This arrangement is frequently resorted to for track circuiting a section of track of a length such as to make the operation of a single track circuit impossible or impractical. The current from battery 2B is supplied to the rails of section 2T over the back point of contact 6 of relay ITR, through a resistor 4, and code following track relay 2TB responds to the impulses of current supplied to the rails of section 2T. Thus, relay ITR responds to the coded current supplied to the rails of section IT by relay C, and relay 2TB, responds to the coded current supplied to the rails of section 2T by relay ITR. The relay 2TB may be utilized for controlling traffic controlling devices in accordance with the coded current with which it is supplied.

As pointed out previously, I have found that the rails and ballast of a coded track circuit may in some respects be similar to a storage battery. That is, the. rails and ballast may receive and store a charge of energy during the on periods of the coded current. This stored current is dis- 5 charged into the code following track relay during the off periods with the result that the proper operation of the code following track relay may be interfered with.

I have also discovered that if the rails of the track circuit are shunted by a path of comparatively low resistance during the off periods of the coded current, the stored energy in the rails and ballast will be discharged and shunted away from the code following track relays so that these relays are permitted to function properly.

I provide this shunt path across the rails of section IT in one form by connecting rail I to the back point of contact 5 of relay 0 by means of connection I, and across the rails of section 2T in another form by connecting rail I to the front point of contact 6 of relay ITR by means of connection 8. It will be obvious that when relay C is deenergized so that the back point of contact 5 is closed, the rails I and 2 of section the coded energy is again supplied to the rails,

the shunt paths, of course, will be opened.

Both forms of my invention, therefore, provide simple and reliable means for reducing or minimizing the storage battery efiect of coded direct current track circuits so that the code following track relays associated with such track circuits may function properly.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In combination, a first and a second section of railway track, means for supplying coded current to the rails of said first section, a code following track relay for said first section responsive to said coded current, means including a back contact of said track relay for repeating said coded current into said second section, and means including a front contact of said track relay for closing a shunt path across the rails of said second section to thereby discharge the energy stored in the rails and ballast of said second section in order to eliminate distortion of the coded current repeated into said second section.

FRANK H. NICHOLSON L 

